One well known technique for dispensing medicinal fluids is by use of a medical syringe. Syringes of this type commonly include a cylindrical barrel which accommodates the medicinal fluid, and a plunger which is movable within the barrel so as to dispense the fluid contained therein. The fluid is dispensed or injected through a hypodermic needle or IV access device. In certain types of syringes, the hypodermic needle or I.V. access device may be attached to the barrel by means of an injection holder supported by the barrel. In other types of syringes, the hypodermic needle may be directly affixed to the syringe, such as by a staked needle arrangement.
In many instances, the syringes are designed for single dosage. In these single dosage situations the medicinal fluid may be prefilled in the barrel of the syringe. Such a prefilled single-use syringe is provided with the hypodermic needle or IV access device attached to the injection holder or, in the case of a staked syringe, is directly affixed to the distal end of the syringe barrel. A safety cap or cover is placed over the syringe to enclose the needle or IV access device. The safety cap may be removed by the user so that the medicinal fluid contained within the barrel can be injected.
During assembly of the syringe, the injection member, namely the hypodermic needle or IV access device, may be frictionally attached to the injection holder by placing the injection member within the cover and then attaching the cap to the injection holder. In this manner, the injection member need not be directly handled. The attachment of the cover to the injection holder secures the injection member to the injection holder so that when the cover is removed, the injection member is retained on the injection holder for use. Alternatively, the needle or I.V. access device can be placed onto the injection holder, thereafter placing the cover over the needle or I.V. access device.
Prior to shipment of the assembled prefilled syringe, the syringe must undergo certain secondary operations. One of these secondary operations includes exposing the syringe to a sterilizing treatment, such as a steam treatment or an ethylene oxide (EtO) gas treatment. To assure that the steam or EtO gas completely envelops the entire syringe, especially the injection member, the cap is designed to be retained on the injection holder guide such that the sterilizing medium can penetrate beneath the cap and around the injection member. However, the temperature or pressure variations to which the syringe is subjected during such sterilization procedures, coupled with other forces during shipment and handling, may have a tendency to dislodge the injection member from its frictional securement with the injection holder. In addition, and particularly in the case of plastic components, such procedures may cause variations in the fit between the injection member and the injection holder. Thus, when the syringe is delivered to the user, and the cover is removed from the holder, it may be found that the injection member is not properly seated on the injection holder. This would require the user to re-secure the injection member to the syringe. This action may present a safety hazard and/or result in contamination of the sterilized surface of the injection member.
It is therefore desirable to provide a syringe assembly which assures the retentive frictional securement of the injection member to the injection holder prior to use.